Onychoscopy: Dermoscopy of the Nails.

Onychoscopy is the examination of the nail unit using a dermoscope. The dermoscopic criteria for a valid diagnosis have been developed and assessed in numerous papers. However, in all nail alterations that are suspicious or potentially malignant, a surgical intervention with subsequent histopathological evaluation should be performed. A simple visualization may not be helpful in diagnosing many nail conditions nor is a nail biopsy diagnostic in all cases. Onychoscopy is a valuable aid in enhancing visible nail features and in revealing cryptic features of diagnostic value.